Counterbalancing device



Oct. 22,=1940. Q R. ATHY ET AL 2,218,967

GOUNTERBALANCING DEVICE Oct. 22, 1940. C, R, ATHY ET AL 2,218,967

CQUNTERBALANCING DEVICE Filed Aug. 3l, 1938 2 Sheets-Slxeetl 2 ATTORNEYS Patented Oct. 22, 1940 UNITED` STATESv PATENT ori-ficsooUNTERBALANoING DEVICE Application August 31, 193s, serial No. 227,792

'z Claim.

Our invention relates to a counterbalancing device. It has to do, moreparticularly, with a counterbalancing device that isy adapted to be usedin conjunction with an oil well pumping mechanism, although it is notnecessarily limited thereto.

One of the objects of our invention is to provide a counterbalancingdevice which may readily be applied to or removed from the crankshaft ofoil well pumping mechanism and which is of such a nature that it willeffectively counterbalance a portion of the Well load.

Another object of our invention is to provide a counterbalancing deviceof the type indicated which is of such a nature that the.counterbalancing effect thereof may readilybe varied.

Another object of our invention is to provide a counterbalancing devicewith a crank associated therewith, the device being of such a naturethat a long pumping stroke is provided without an unnecessarily heavycounterbalance. Another object of our invention is to provide a crankcounterbalancel which is so .constructed that the counterbalance weightsassociated therewith will have a maximum eiTect. f

Another object of our invention is to provide a crank counterbalance ofthe typeindicated which -includes weights that are adjustable tovariousv positionsy to vary the counterbalance effect and which isprovided with safety means for locking such weights in position toprevent vibration, etc., from moving them out of position.

The preferred embodiment of our invention is illustrated in theaccompanying drawings Wherein similar characters of reference designatecorresponding parts and wherein:

Figure l is a front elevation of a counterbalance device constructed inaccordance with our invention.

Figure 2 is a Vertical section taken substantially along line 2 2 ofFigure l.

Figure 3 is a vertical section taken substantially along line 3-3 ofFigure 1.

Figure 4 is a perspective View illustrated in Figure 1.

Figure 5 is a perspective View illustrating a member used in mountingweights on our counterbalancing device.

Figure 6 is a view similar to Figure l but showing the weights in adifferent position on the counterbalancing device. v

Figure 7A is a front elevation of a slightly modied form of ourcounterbalanee device.

of the structure Figure 8 is a similar view of another modified form ofour device.

With reference to the drawings, we have illustrated our device mountedon the crank shaft l of a well pumping mechanism. Our device comprises asegmental crank member 2 which includes an annular rim 3 and anapertured platelike portion 4 integrally joined together. A split hub 5is formed on member 2 and is disposed in surrounding relationship to theouter end of the shaft i. The crank arm proper 6 is formed as anintegral portion of the member 2. arm at its upper end is associatedwith the split hub 5 and has a split T in its upper end Which is inalignment with the split of the hub 5. A

bolt structure extending transversely through the upper end of the crankarm 6 serves to draw the split upper end of the crank arm tightlytogether and simultaneously draw the split hub 5 tightly around theshaft i. A key Q may be provided for aiding in securing the member 2nonrotatably on the crank shaft l. Due to the split hub-construction andthe associated split portion of the crank arm, it will beapparent thatthe counterbalance device may readily be applied to or removed from theshaft i. The crank arm 6 and the member 2 may be cast as a single unit.

The crank arm 6 is provided with a plurality of radially spaced openingsl each of which is adapted to= receive the Wrist pin which is commonlyused for connecting the pitman of a well pumping mechanism to the crankarm. It will be noted that the crank arm protrudes beyond the peripheryof the member 2. This is an important feature inasmuch as it results inlonger crank radii lwithout increasing the radius of the member 2. Thus,with this' device a long pumping stroke is provided while at the sametime a counterbalance having an unnecessarily large radius is avoided.Thus, a great saving in space also results.

It will be noted that the crank is of1wheel-like structure but that asegment of the rim 3 of `the member 2 is omitted at a pointdiametrically opposite to the protruding portion of the crank arm. Thus,the rim 3 extends upwardly on both sides beyond the crank shaft i but isnot continuous. This facilitates the application of counterbalanceweight units Il to the member 2. Also, due to the fact that this portionof the rim is omitted, the counterbalance weight units li are moreeffective when they are on the crank arm side of the shaft I since anyweight on. the opposite side of the crank shaft from the counter- Thiscrank upper end through which the bolts i8 pass.

weight units I I tends to counteract the effect of such weight.

'Ihe counterweightunits I I are attached to the member 2 by thestructure which will now be described. It will be apparent from thedrawings that the rim 3 of the member 2 has a continuous slot I2 formedin its peripheral edge on each side of the crank arm E. These slots aresubstantially T-shaped in cross-section. Each slot extends along the rim3 fromV a point adjacent crank arm 6 to the end of the rim and is openat its outer end due to the fact that the segment of the rim is omitted.Each slot is adapted to receive member I3 of the shape illustrated inFigure 5, one of which is provided for each counterweight Il. Eachmember I3 is substantially T-shaped in cross-section. Its lower surfacesare curved as at I4 and I5 in accordance with the curvature of the rim3. The upper or inner surface is provided with a bolt hole I6 adjacenteach end and a countersunk socket Il in association therewith forreceiving a square head formed on the inner end of a bolt I8 used insecuring a counterweight I I to the member 2.

Each of the counterweights I I is of substantially the shape illustratedin the drawings. Each counterweight II is provided in one face thereofwith a socket or receptacle 20 for receiving and holding additionalweights. Each counterweight II is provided with a pair of openings 2I atits Removable nuts 22 are provided on the outer ends of these bolts andcan readily be reached since they are located in the receptacle 20formed in the counterweight.

In mounting each coun-terweight II on the member 2, the member I3 withthe bolts I8 positioned therein and depending from the lower surface.thereof is slipped into the open end of one of the slots I2. The memberI3 may then lbe slid through the slot I2 until it is adjacent the lowerportion ofthe member 2 at which time the bolts I8 may be passed throughthe openings 2| of t-he lcounterweight II and the nuts 22 may beapplied. Since the heads of the Ibolts rit into the sockets I'l, thebolts will not rotate during this operation. The nuts may be tightenedto clamp the counterweight II tightly against the periphery of the rim3. It will be apparent that Vby loosening the nuts, the counterweigh-tunit I I may ibe moved on the rim 3 to :any desired position. When thenuts 22 are again tightened, the counlterweight will again be clampedIin adjusted position. Thus, the counterweight units II may ybe adjustedto the position indicated in Figure 1 where they abut each other asindicated at 23 and their counterbalance effect is the greatest, or maybe separated to any `desired extent to vary the counterbalancing eiiect.'I'he weights II, or either of them, may be moved to any selectedposition between the position illustrated in Figure 1 and the positionillustrated in Fig-` ure 6. In order to facilitate this adjustment, theinner peripheral wall of lthe rim 3 is provided with a plurality ofcircumferential-ly spaced apertures 24. When the nuts 22 Iare loosened,the counterweight units -I I may be moved along the rim 3 either by theforce of gravity or by prying with a crow bar. Openings 2t will serve as"toe holds or fulcrum points for the crow bar.

In order to lock the weights II in adjusted position so that there willbe no danger of vibration, etc., moving them along rim 3, we provide aplurality of teeth I9 which are formed on the rim 3 along the peripherythereof. These teeth lare adjusted to interlock with corresponding teethI9 formed lon the inner edge of each of the weight units I I. Thus, eventhough the nuts on the clamp bolts 2| become loosened somewhat due tovibration, the interlocking structure will prevent movement of .theweights along the lIhe rim 3 is provided at each end with transverselyextending removable Ibolts 3 which will normally prevent members I3 fromslipping out of the `open ends of slots I2.

The socket or receptacle 20 formed in. each of lthe counterweight umts II is adapted to receive one or more additional weight elements 25. Theseweigh-t elements are of substantially the same shape .as the receptacleand are secured in position by transversely extending bolts 26 whichextend through ali-gning openings in the weights 25 and the units II.The top edges of the weights 25 are preferably spaced from the top wallof the socket or receptacle 20 so that access to the nuts 22 may be hadwithout removing the weights 25. Thus, the weight of the counterbalan-ceunit may be varied by applica-tion of the weights 25 to the units I I orremoval of the weights therefrom.

It will `be apparent from the above description that we have provided acounterbalance device having many desirable features. Due to the split-hub construction, the device may readily be applied to or removed fromthe :crank shaft. Furthermore, it will be apparent that thecounterbalance device is so lconstructed that the counterbalance effec-tthereof may readily and quickly be varied by either or both of twomethods. That is, by adjusting :the angular relationships ofcounterweight units II -and/or by adding or y Due to the fact removingweight elements 25. that the crank arm 6 protrudes :beyond the peripheryof the wheel-like portion 2, a long pumping stroke is provided withoutunnecessarily in- -creasing the radius of the counterbalance device. Dueto the tact that 'the upper portion of the rim of the member 2 isomitted, the effect of the counterweight units II is increased.Furthermore, application of the means for securing the units II to therim 3 is facilitated by the omission of the segment of the rim.

For :certain uses we prefer to lhave the crank mem-ber 2 of thesegmental for-m as previously described. For example, we prefer thisconstruction for front crank or twin crank applications. In theseapplications, it is never necessary to swing the counterweight unitsover .the top of the crank. However, for some other uses, a completecircle crank of the type illustrated in Figure '7 may -be preferred. Forexample, this construction would be preferred for Iback crankapplications where it is desirable under certain conditions to vswingthe lcourrterweight units over the top yand clamp lboth weights to oneside of the crank.` Thus, in the form shown in Figure 7, the member 2a.is of disk-'like Iform and has :a rim 3a in the form of a continuouscircle. 'Ilhe inner periphery of this rim is ycutaway at the top thereofso that a slot or opening 2l is formed which is just of sufficientlength to permit the insertion of each member I3 into the slot I2a. Theteeth I9a are disposed along :the entire periphery of rim 3a. Thus, itwill be apparent that with this structure, the weights I I or either ofthem may be adjusted over the top of the crank 2a and may be clamped inany desired position. 'The two weights may lbe :disposed directlyopposite member 6 or they may both be exactly the same manner aspreviously described.

It Will be apparent that our structure has many advantages, some ofwhich have been mentioned yand others which will ibe apparent from thedrawings and the following claims..

Having thus described our invention, what We claim is:

1. A counterbalance device of the -type described comprising aWheel-likestructure, a crank arm formed as an integral part of saidWheellike structure, counterweights adjustably secured to the peripheryof saidv structure, said Wheellike structure having slots ofT,crosssection formed in its periphery, a separate block of T-cross-section disposed Within each of said slots.

in such a manner that longitudinal movement thereof Will be permittedbut radial movement will be precluded, said block carrying bolts Whichproject radially through said slot and are attached to one of saidWeights, said Wheel-like structure having a segment thereof omitted sothat the ends of said slots Will be open to permit positioning of saidblocks'therein.

2. A counterbalance device of the type described comprising a Wheel-likestructure, a crank arm formed as an integral part of said Wheel-likestructure, said crank arm extending from the center of said structureand radially beyond'the circumference of said structure, said Wheel-likestructure'having a segmental portion omitted at' a point diametricallyopposed to the point Where said crank arm extends beyond thecircumference of said structure, said Wheel-like structure having a rimformed on its periphery and having a pair of undercut slots formed insaid rim at the outer side thereof, each of said slots extending fromthe crank arm circumferentially to the end of said Wheel-like structure,means for securing a counterweight to the rim at each side of theprojecting portion of said crank arm, said means comprising a memberfitting into said undercut slot in such a manner that it is free to move1ongitudinally thereof but is precluded from moving radially thereof,said member' carrying bolts which project radially through said slot andare attached to one of said Weights, each of said i.' Weights beingprovided with teeth on `its innerk edge and said rim being provided withteeth on l its outer side which interfit with each other when securing acounterweight to the rim, said means the counterweight is clamped inposition.

3. A counterbalance device of the type decomprising a separate elongatedmember tting into said undercut slot in such a manner that it is free tomove longitudinally-thereof but is lprecluded from moving radiallythereof, said member carrying bolts which project radially through saidslot and are attached to said counterweight,l

said counterweight being provided with teeth on its inner edge and saidrim being provided with teeth on its outer side which intert With each.

other when the counterweight is clamped in position by said bolts.

4.' A counterbalance device of the type described comprising a crankstructure having a rim on its periphery, a counterweight unit mounted onsaid rim and being supported solely by, said rim, adjustable bolts forclamping said counter- Weight-unit to said rim, said counterweight unitbeing provided with teeth on its inner edge and said rim being providedwith teeth on its outer side which .interfltjwith each other when thecounterweight is clamped in position by said bolts.

v5. A counterbalance device of the type de-` scribed comprising aWheellike structure, a crank arm formed as `vanvintegral part of saidwheellike structure, said crank arm extending .from the center of saidstructure and radially beyond the circumference of said structure, saidWheellike structure having-a segmental portion omitted at a pointdiametrically opposed to the point Where said crank arm -extends beyondthe cir` cumference of said structure, said Wheel-like structure havinga rim formed on its periphery A.

said rim at the outerv side thereof, each of said slots extending fromvthe crank arm circumferentially to the end of said Wheel-like structure,means for securing acounterweight to the rim at each side of theprojectingportion of said crank arm, said means comprising a shoe memberfitting into said undercut slot in such a manner that itis free to movelongitudinally thereof but is precluded from moving radially thereof,said member having an arcuate surface which l and having a pair ofundercut slots formed in contacts with the adjacent arcuate surface or"said rim and carrying detachable bolts which pro-'- ject radiallythrough said slot and are attached to one of said Weights.

6. A counterbalance device of the type described'comprising a Wheel-likestructure, said Wheel-like structure having a rim formed on itsperiphery and having an undercut slot formed in said rim at the outerside thereof, means for se curing a counterweight to the rim, said meanscomprising a separate elongated shoe memberl fitting into said undercutslot in such a manner f that it is freeto move longitudinally thereofbut is precluded from moving radially thereof, said shoe member carryingdetachable bolts which project radiallythrough said slot and areattached to said counterweight.

. '7. A counterbalance according to claim 6 wherein the inner Wall ofsaid rim is provided with apertures at spaced intervals through which atool may be inserted into contact with lsaid elongated shoe member. r

' CLIFFORD R. ATHY.

ROY C. PFEIL.

